Thresher sharks visit "cleaning stations"

Scientists filmed sharks off the coast of the Philippines visiting a tropical seamount - or undersea mountain. This is a habitat for cleaner fish, which nibble off parasites and dead skin. The sharks repeatedly visited the station and swam slowly around, giving the fish time to delouse them.

This is the first time the behaviour has been seen in this species and the researchers say it shows how vital these shallow reef habitats are for the large, threatened predators.